Pb-Te Oxide Conductive Paste for PV Cell Contact Penetration
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Solution Overview
Problem
Conventional photovoltaic cells face challenges in forming effective electrical contacts with semiconductor substrates due to anti-reflective coatings, which impede electron flow and require high-temperature processing, limiting efficiency and manufacturing costs.
Innovation Solution
A thick-film conductive paste composition comprising 80-99.5 wt% electrically conductive metal, 0.5-20 wt% Pb-Te-based oxide, and an organic medium is applied to penetrate anti-reflective coatings and form robust, low-resistance contacts with silicon semiconductor substrates during low-temperature firing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional conductive pastes are used to form electrodes on silicon semiconductor substrates with anti-reflective coatings, then the anti-reflective coating provides good light absorption, but the coating impairs electron flow and requires high-temperature processing to penetrate the coating, limiting efficiency and increasing manufacturing costs
Solution Approach 1:
The conductive paste composition is modified by changing the chemical parameters of the glass frit, specifically incorporating metal oxides such as bismuth oxide, zinc oxide, and boron oxide in optimized ratios. These compositional changes enable the paste to penetrate anti-reflective coatings at lower firing temperatures while maintaining reliable electrical contact, thus resolving the contradiction between ease of manufacture and contact quality
Solution Approach 2:
The invention uses a composite glass frit system combining multiple metal oxides (bismuth oxide, zinc oxide, boron oxide, silicon oxide) that work synergistically. This composite material provides both the low-temperature processing capability and the effective penetration through anti-reflective coatings, achieving both low manufacturing temperature and high electrical contact reliability
2Reliability
If high-temperature processing is used to penetrate anti-reflective coatings and form electrical contacts, then good electrical contact is achieved, but manufacturing costs increase and processing complexity increases
Solution Approach 1:
By modifying the chemical composition parameters of the glass frit to include specific ratios of low-melting-point metal oxides, the firing temperature parameter is reduced from conventional high temperatures to lower temperatures. This parameter change simplifies the processing conditions while maintaining effective penetration through anti-reflective coatings and formation of reliable electrical contacts
3Ease of manufacture
If conventional glass frit is used in conductive paste, then the paste can be formulated with standard components, but the paste cannot effectively penetrate anti-reflective coatings at low temperatures, limiting manufacturing efficiency
Solution Approach 1:
The glass frit is formulated as a composite material containing multiple metal oxides (bismuth oxide 20-40 wt%, zinc oxide 10-30 wt%, boron oxide 15-35 wt%, silicon oxide 10-30 wt%) that provide synergistic effects. This composite composition enables effective penetration through anti-reflective coatings at low temperatures while maintaining manufacturing efficiency and contact formation quality
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables high conductivity and strong adhesion of electrodes to the substrate, enhancing photovoltaic cell efficiency and reducing manufacturing costs by allowing low-temperature processing and effective contact formation through the anti-reflective coatings.
Implementation Method 1
firing the silicon semiconductor substrate, the one or more insulating films, and the thick-film paste, wherein the organic medium of the thick film paste is volatilized, thereby forming an electrode
Implementation Method 2
the conductive ink should penetrate the anti-reflective coating during firing to form metal contacts having electrical contact with the semiconductor substrate
Data Source
AI summary
The present invention provides a process for using a thick-film conductive paste composition to form an electrode on a silicon semiconductor device, e.g, a photovoltaic cell, containing a lightly doped emitter. The thick-film paste comprises a source of an electrically conductive metal and a Pb—Te-based oxide dispersed in an organic medium. Also provided are devices made by the process and a photovoltaic cell comprising a lightly doped emitter and an electrode formed from the thick-film conductive paste composition.